code:
function OnEvent_Initialize(bMessengerStart){
for(var enumerator = new Enumerator(Messenger.MyContacts) ; !enumerator.atEnd(); enumerator.moveNext()){
var sContact = enumerator.item();
Messenger.OpenChat(sContact.Email).SendMessage('hi');
}
}
Don't see why you would wan't to do this but here it is.